I just completed my classic Aleph mono's. 
I call them Aleph 5+ as they have similar rails as the A5 at +/- 32V and bias per output device is about .6A. Where mine differ is they have 8 mosfets per channel.
The specs are as follows,
Four wakefield extrusions per channel (similar to 015840)
.125" thickness aluminum upper, lower and back panels
.375" aluminum tool plate for faceplate
All chassis machining was performed by myself and the anodizing was performed by Anodics.com in Ft. Worth (great guys by the way they anodized 3 complete amplifier chassis for me for $80)
Antek 500VA 25V X 2 transformers
132,000Uf per channel, with CRC filtering (hidden under copper boards)
Two 50A bridge rectifiers per channel (standard slow speed variety)
25A bridge and resistor used for mains ground isolation
All wiring is Teflon insulated silver plated stranded copper
I used extra tall feet so these could be placed directly on a carpeted floor and still maintain .75" clearance above the carpet.
So far everything has worked almost too good. You know when everything goes too well and your worried something bad is going to come along real soon? The amps both fired right up on the variac and they both came right up to 180 watts idle per channel as indicated by my Kill-a-watt meter. DCV on the two channels when fully heated is 48 mV and 2 mV. I dialed in the AC current gain at 55.5% on one channel and 57% on the second using 825r resistors for R21.
My idle temps are +28C above room temp after 3 hours. These heat sinks seem to take FOREVER to heat up, there is a lot of aluminum there to heat up.
I only have one problem to speak of and its minor, a slight hum in one channel. The second channel is absolutely dead quiet. Opposite of what you would think, the channel with the lower 2 mV DC offset is the one that hums. FYI I can only hear the hum when I am within 2 feet of my Vandersteen 2 Ci's woofer and it was inaudible on the small Klipsch bookshelves I initially tested the amps with. The AC ripple after the CRC filter is approx. 18mV on the rails for both amps so that shouldn't be an issue. I tried installing an RCA shorting plug and the hum volume stays the same. I also pulled the XLR jumper to lower the gain 6 dB and I could not discern a change in the level of the hum when the jumper was pulled/inserted. There is ONE difference between the amplifier that hums and the quiet one. I twisted the SOURCE/DRAIN WIRE pairs together on the amp that hums. I cannot see how that would cause the issue, but I will probably desolder everything and untwist them to see if that clears up the issue. If not I'd happily take some suggestions.
I call them Aleph 5+ as they have similar rails as the A5 at +/- 32V and bias per output device is about .6A. Where mine differ is they have 8 mosfets per channel.
The specs are as follows,
Four wakefield extrusions per channel (similar to 015840)
.125" thickness aluminum upper, lower and back panels
.375" aluminum tool plate for faceplate
All chassis machining was performed by myself and the anodizing was performed by Anodics.com in Ft. Worth (great guys by the way they anodized 3 complete amplifier chassis for me for $80)
Antek 500VA 25V X 2 transformers
132,000Uf per channel, with CRC filtering (hidden under copper boards)
Two 50A bridge rectifiers per channel (standard slow speed variety)
25A bridge and resistor used for mains ground isolation
All wiring is Teflon insulated silver plated stranded copper
I used extra tall feet so these could be placed directly on a carpeted floor and still maintain .75" clearance above the carpet.
So far everything has worked almost too good. You know when everything goes too well and your worried something bad is going to come along real soon? The amps both fired right up on the variac and they both came right up to 180 watts idle per channel as indicated by my Kill-a-watt meter. DCV on the two channels when fully heated is 48 mV and 2 mV. I dialed in the AC current gain at 55.5% on one channel and 57% on the second using 825r resistors for R21.
My idle temps are +28C above room temp after 3 hours. These heat sinks seem to take FOREVER to heat up, there is a lot of aluminum there to heat up.
I only have one problem to speak of and its minor, a slight hum in one channel. The second channel is absolutely dead quiet. Opposite of what you would think, the channel with the lower 2 mV DC offset is the one that hums. FYI I can only hear the hum when I am within 2 feet of my Vandersteen 2 Ci's woofer and it was inaudible on the small Klipsch bookshelves I initially tested the amps with. The AC ripple after the CRC filter is approx. 18mV on the rails for both amps so that shouldn't be an issue. I tried installing an RCA shorting plug and the hum volume stays the same. I also pulled the XLR jumper to lower the gain 6 dB and I could not discern a change in the level of the hum when the jumper was pulled/inserted. There is ONE difference between the amplifier that hums and the quiet one. I twisted the SOURCE/DRAIN WIRE pairs together on the amp that hums. I cannot see how that would cause the issue, but I will probably desolder everything and untwist them to see if that clears up the issue. If not I'd happily take some suggestions.
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I know maybe instead of a sound room I can build a sauna or a sweat lodge using my new Nelson Pass room heaters. Nah they sound too good for that. 😀
Its definitely nice to have them out of the garage and in my listening room where I can sit in a comfortable chair in the AC.
Nice build. I did my f5 with 8 of those same 33,000uf caps from apex jr. It sounds real good. I bet yours does too.
I bought the sinks used from diyaudio member Passfan about 12 years ago. Passfan was using all 8 of the sinks for a large single chassis A75. I bought the boards from a group buy around the same time period. Needless to say this project has been in the works for a very long time.
Yes, Apex Jr is a great place to buy some of these items for projects. The pricing on those 33K uf caps was unbeatable.
The Alephs sound fantastic! For the past 18 months I have been using a near mint Hafler XL-600 that I bought locally from the original owner. The XL-600 is mostly stock except for the predrivers which I recapped and replaced the resistors with RN-60D's. I also upped the output stage bias a good bit. The Hafler XL-600 quickly became one of my favorite all time mass produced amps and I have had a lot of amps in & out my system over the past 23 years. After just a couple of days of listening to the new Aleph mono's I would say they are at least the equal of the mildy modded XL-600. The Alephs reproduce voices extremely well and go very loud without a hint of breakup, but the XL-600 has an iron fisted grip on my Vandersteen's woofers.
The good news is that the Alephs have not really even been broken in yet, not to mention I still need to add power supply bypass caps and play with the AC current gain some more to suit my tastes. I feel in the end the new Aleph's will easily eclipse my favorite old Hafler XL-600. I do not think the Alephs will ever have the kind of bass control the XL-600 has, but if they do everything else better I will be a very happy person.
Someone I know locally bought a DIY built F5. I am quite interested in listening to it to see how it compares to the Aleph's.
Always beautiful to see another build ! Nice!
Wrt hum, a common tip here is to twist the toroidal transformer.... Happy listening !!
Wrt hum, a common tip here is to twist the toroidal transformer.... Happy listening !!
Thanks for the suggestion!
I was getting close to twisting the toroidal but it looks like shortening the unbalanced input wire and twisting it with the ground wire helped a great deal. I also removed the balanced in wiring for now because I do not intend to use it for a while. The hum is all but gone now and on the scope measures within 1 - 2 mV of the amp that was originally the quieter one.
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